This invention relates to a cylindrical lock for mounting on a door panel and, in particular, to an improved cylindrical lock assembly with use lever-type handles.
Cylindrical locks utilized in exterior door applications must be made to withstand more severe environments and higher security usage than those utilized on interior doors, especially when lever-type handles are used. Potential damage can result from vandalism, burglary and general misuse and/or abuse, and such damage is often magnified by the availability of the lever handle to exert considerable torque on the lock assembly. Overloading of such lock assembly may jam and disable it, or damage it to the extent that the door may be forced open.
An improved cylindrical handle lock for heavy duty exterior door application has been disclosed in U.S. Pat. No. 4,869,083 to DeMarseilles, et al., the disclosure of which is incorporated herein by reference. This patent utilizes a pair of tongue members extending inwardly from support plates which mate with corresponding openings in the lock chassis. However, in order to provide for the greater resistance to damage in such heavy duty lock mechanisms, it is necessary to drill additional holes in the door panel outside of the bore which receives the lock chassis. These additional holes permit the passage of thru bolts which provide resistance and support against rotation of the support plates and which connect the lock roses covering the support plates.
In medium duty applications, for sake of simplicity, it is not generally necessary to utilize drilled holes outside of the door panel bore. Nevertheless, for strength reasons, it is still desirable to have bolts connecting the support plates to the lock chassis, along with thru bolts connecting the two exterior roses. However, this presents the problem that if the thru bolts connecting the roses and the fasteners connecting the support plate to the chassis are configured to pass separately within the diameter of the door panel bore, valuable space necessary for the lock assembly mechanisms are eliminated. Up to now, the only alternatives have been either: 1) reduce the space available for the lock mechanism so as to permit both sets of bolts to pass within the bore diameter, with the result of weakening the mechanism or making it less secure, or 2) drill extra holes outside of the bore diameter to accommodate the thru bolts for the roses, with the result of making installation more difficult.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide an improved lever handle lock assembly which is highly resistent to abuse, vandalism and damage in general.
It is another object of the present invention to provide a strengthened cylindrical lock assembly which is easily installed in conventional door opening without the necessity of drilling additional holes outside of the bore diameter.
It is a further object of the present invention to provide an improved cylindrical lock assembly which meets the above objects but which does not eliminate space in the lock chassis devoted to the lock mechanisms.